Scanning unit for an angle-measuring device

ABSTRACT

A scanning unit for determining a relative angular position of an angular scale that is rotatable about an axis relative to the scanning unit includes a circuit board having a first surface and a second surface and evaluation electronics. A detector assembly is disposed in a manner that enables scanning of the angular scale located opposite the first surface of the circuit board. A housing body includes: slots extending circumferentially about the axis; lands in each case extending axially between two of the slots such that the housing body is axially flexible but torsionally and radially rigid; and a bottom disposed axially between the slots and the circuit board.

CROSS-REFERENCE TO PRIOR APPLICATION

Priority is claimed to European Patent Application No. EP 19 152 248.1,filed on Jan. 17, 2019, the entire disclosure of which is herebyincorporated by reference herein.

FIELD

Angle-measuring devices are used, for example, in rotary encoders todetermine the angular position of two relatively rotatable machinesparts.

BACKGROUND

In scanning units of inductive angle-measuring devices, it is common toapply excitation coils and receiver coils in the form of conductivetraces to a common circuit board that is fixedly attached to, forexample, a stator of a rotary encoder. Located opposite this circuitboard is a further component which has an angular scale in the form ofelectrically conductive regions formed thereon at periodic intervals asa graduation structure and which is non-rotatably connected to the rotorof the rotary encoder. When an electric excitation field is applied tothe excitation coils, then angular-position-dependent output signals aregenerated in the receiving coils during relative rotation between rotorand stator. These output signals are then further processed inevaluation electronics.

A fundamental distinction is made between angle-measuring devices withintegral bearings and angle-measuring devices without integral bearings,hereinafter referred to as bearingless angle-measuring devices.Angle-measuring devices with integral bearing typically have relativelysmall rolling-element bearings, so that the relatively rotatablecomponent groups are disposed in a defined axial and radial positionrelative to each other within the respective angle-measuring device. Incontrast, in the case of bearingless angle-measuring devices, care mustbe taken to ensure that the relatively rotatable component groups arefixed in the correct position, in particular at the correct axialdistance relative to one another, while being mounted on a machine.

The Applicant's German Patent Application DE 10 2008 046 741 A1describes an angle-measuring device having a scanning unit with aconnector. Furthermore, EP 0 845 659 A2 describes a scanning unit thatis attached to a drive mechanism.

SUMMARY

In an embodiment, the present invention provides a scanning unit fordetermining a relative angular position of an angular scale that isrotatable about an axis relative to the scanning unit. The scanning unitincludes a circuit board having a first surface and a second surface andevaluation electronics. A detector assembly is disposed in a manner thatenables scanning of the angular scale located opposite the first surfaceof the circuit board. A housing body includes: slots extendingcircumferentially about the axis; lands in each case extending axiallybetween two of the slots such that the housing body is axially flexiblebut torsionally and radially rigid; and a bottom disposed axiallybetween the slots and the circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described in even greaterdetail below based on the exemplary figures. The present invention isnot limited to the exemplary embodiments. All features described and/orillustrated herein can be used alone or combined in differentcombinations in embodiments of the present invention. The features andadvantages of various embodiments of the present invention will becomeapparent by reading the following detailed description with reference tothe attached drawings which illustrate the following:

FIG. 1 is a side view showing a circuit board with a contact carrier aspart of the scanning unit;

FIG. 2 is a perspective view showing the circuit board with the contactcarrier;

FIG. 3 is a cross-sectional view showing a housing body;

FIG. 4 is a cross-sectional view showing a housing body with the circuitboard and the contact carrier;

FIG. 5 is a perspective view showing the scanning unit;

FIG. 6 is a cross-sectional view showing an angle-measuring device withthe scanning unit in the mounted condition; and

FIG. 7 is a perspective view showing a scanning unit according to asecond exemplary embodiment.

DETAILED DESCRIPTION

In an embodiment, the present invention provides a scanning unit for an,in particular bearingless, inductive angle-measuring device whichscanning unit is mountable with precise fit on another machine part withrelatively little effort.

Accordingly, an embodiment of the present invention encompasses ascanning unit for determining a relative angular position of an angularscale that is rotatable about an axis relative to the scanning unit. Thescanning unit includes a circuit board having a first surface and asecond surface. The scanning unit further includes at least one detectorassembly which is disposed in manner that enables scanning of theangular scale located axially opposite the first surface of the circuitboard. The scanning unit also includes evaluation electronics, which istypically composed of a plurality of electronic components and often hasan integrated circuit (ASIC component). Furthermore, the scanning unitincludes a housing body having a bottom. The housing body further hasslots extending circumferentially about the axis and lands extendingaxially and circumferentially between two slots. In particular, theslots and lands are configured such that the housing body is axiallyflexible but torsionally and radially rigid. Moreover, the bottom isdisposed axially between the slots and the circuit board, so that inparticular the evaluation electronics is accommodated in a protectedposition between the slots and the circuit board.

In the following, the term “lands” is used to refer to the land- orstrip-shaped regions of the housing body that run or extend with anaxial directional component. Each land is located between two slots, sothat, in particular in the circumferential direction, a slot is disposedon each side of a land.

The detector assembly is capable of generating angle-dependent outputsignals, which can be further processed in the evaluation electronics.Angle-dependent output signals are in particular signals which containinformation about the relative angular position between the angularscale and the scanning unit. The housing body is torsionally rigid,which means that it does not deform, or deforms only to an extremelysmall extent, in response to the introduction of tangentially directedforces. In addition, the housing body may be rigid in a radialdirection.

Advantageously, the scanning unit has lands with a slot disposed axiallytherebetween, so that these lands are axially offset from one another.In particular, the respective lands may be disposed in alignment withone another; i.e., such that they are not offset from one another in thecircumferential direction.

In an embodiment of the present invention, the scanning unit has a firstpair of lands, the lands of this first pair being offset from oneanother in the circumferential direction. For example, the lands may beoffset by 180° or 120° in the circumferential direction. With regard tothe definition of the offset angle, which is in particular a centralangle about axis A, the center of a land (with respect to thecircumferential direction) may in each case be taken as a referenceline.

Advantageously, the scanning unit has a first pair of lands, these landsbeing disposed in a geometric plane whose normal vector is orientedparallel to the axis.

Furthermore, the scanning unit may have a second pair of lands. In thiscase, the lands of the first pair may be axially offset relative to thelands of the second pair. In addition, the lands of the first pair maybe offset in the circumferential direction relative to the lands of thesecond pair. Advantageously, the lands of the first pair are each offsetby the same angle relative to respective lands of the second pair in thecircumferential direction. In particular, the respective lands may beoffset from one another by 60° or by 72° or by 90° or by 120°.

In an embodiment of the present invention, the scanning unit has a firstpair of slots. Advantageously, the scanning unit then has a second pairof slots, the slots of the first pair being axially offset relative tothe slots of the second pair. In particular, the slots of the first pairmay be offset in the circumferential direction relative to the slots ofthe second pair.

Advantageously, at least one of the slots extends over a circumferentialangle of at least 70°, in particular over a circumferential angle of atleast 100° or at least 140°. It is also advantageous if all slots extendover a circumferential angle of the same magnitude or if at least theslots of a pair extend over a circumferential angle of the samemagnitude.

The term “pair” means a group of two elements; i.e., here two slots ortwo lands. This wording does not rule out the possibility that therespective regions of the housing body may have one or more further suchelements (slot, land) in addition to the two elements.

Advantageously, the housing body is elastically deformable in thedirection of the axis over a range of at least 0.5 mm, in particular atleast 1.0 mm, and preferably at least 1.5 mm.

Advantageously, the housing body has a stop surface having a normalwhich has a directional component parallel to the axis. The object ofthis is in particular to allow the housing body to rest axially againstthe stop surface.

Advantageously, the housing body is designed such that the bottom andthe lands are monolithically formed from a single piece; i.e., machinedout of a single piece. For example, the entire housing body may bemonolithically formed or include at least one monolithic sub-bodyincluding the bottom and the lands as integral parts thereof.

Advantageously, the scanning unit has a contact carrier which encloseselectrical contacts for creating a plug-and-socket connection and whichis mounted on the second surface of the circuit board, so that thecontacts extend in a direction having an axial component. In particular,the contact carrier has a cylindrical outer wall whose axis of symmetryis the axis around which the angular scale is rotatable. Finally, thescanning unit includes a housing body with an opening having an innerwall. The contact carrier extends into the opening, a first elasticelement being disposed under radial preload between the inner wall ofthe opening and the outer wall of the contact carrier, so that thecontact carrier is centered with respect to the inner wall of theopening. The circuit board is torsionally rigidly attached to thehousing body such that it is radially spaced therefrom by a first gap.

The detector assembly may be mounted, for example, on the first surfaceof the circuit board. If the detector assembly is embodied as one or aplurality of receiver windings or as magnetoresistive conductive traces,the detector assembly may also have disposed thereon a thin layer whichin particular has insulating properties and provides mechanicalprotection.

In an embodiment of the present invention, the first gap is filled withan adhesive.

Advantageously, the first elastic element takes the form of an O-ringwhich is disposed centrally with respect to the axis and which, inparticular, is deformed due to the radial preload.

Advantageously, the circuit board is torsionally rigidly attached to thehousing body such that it is axially spaced therefrom by a second gap,which second gap may also be filled with an adhesive.

In an embodiment of the present invention, the outer wall of the contactcarrier is geometrically shaped as a cylindrical shell.

Furthermore, the opening may have a rotationally symmetric innersurface, the above-mentioned axis being the axis of symmetry of theinner surface. For example, the inner surface may be the inner contourof a hollow cylinder.

Advantageously, the housing body has a bottom. Furthermore, the circuitboard is mounted to the housing body in such a way that the evaluationelectronics; i.e., electronic components of the evaluation electronicsare located between the bottom and the circuit board. In this case, thebottom may have a hole in which is mounted a sleeve to receive thecontact carrier. A particularly economical design can be achieved byusing a standardized housing coupling as the sleeve. In a possiblealternative design, no additional component is used, so that the contactcarrier extends directly into a (threaded) hole in the bottom.

Advantageously, a second elastic element, which may in particular takethe form of an O-ring, is provided between the sleeve and hole.

The angle-measuring device may be designed as an inductiveangle-measuring device or may be based on an optical, magnetic orcapacitive principle. Furthermore, the angle-measuring device, which hasan angular scale, a scanning unit and evaluation electronics, ispreferably designed as a bearingless angle-measuring device.

Other details and advantages of the scanning unit according toembodiments of the present invention will be apparent from the followingdescription of two exemplary embodiments, taken in conjunction with theaccompanying drawings.

A portion of a scanning unit intended for use in an angle-measuringdevice is shown in a side view in FIG. 1 and in a perspective view inFIG. 2. Accordingly, the scanning unit includes, among other things, adisc-shaped or circular circuit board 1 on the basis of a rigid,fiberglass-reinforced epoxy resin. Circuit board 1 naturally has a firstsurface 1.1 and a second surface 1.2 opposite the first surface 1.1. Inthe exemplary embodiment presented here, the scanning unit is based onan inductive measurement principle. Accordingly, a detector assembly 2disposed on first surface 1.1 is embodied as a plurality of receiverwindings. Also disposed on first surface 1.1 are a plurality ofexcitation traces 10.

Second surface 1.2 has mounted thereon, among other things, electroniccomponents 3.1 of evaluation electronics 3. A contact carrier 4 is alsomounted on second surface 1.2 of circuit board 1, for example with theaid of surface-mount technology (SMT). Contact carrier 4 encloseselectrical contacts 4.1 (FIG. 2) suitable for creating a plug-and-socketconnection, the contacts 4.1 extending in a direction parallel to anaxis A. Contact carrier 4 has an outer wall 4.2 or outer surface whichgeometrically corresponds substantially to a cylindrical curved surface.Outer wall 4.2 has a circumferential groove in which is disposed a firstelastic element 6, here an O-ring.

The scanning unit further has a housing body 5, as shown, for example,in FIG. 3. Housing body 5 includes a bottom 5.1 disposed within andintegrally formed with a rigid annular portion of housing body 5. Thebottom has a hole centrally formed therein with respect to axis A, thehole having a sleeve 5.11 threadedly received therein. A second elasticelement 7 is disposed axially between a flange of sleeve 5.11 and bottom5.1. Here, second elastic element 7 is also embodied as an O-ring.Sleeve 5.11 has a through-opening H and, accordingly, an inner wall5.111. Inner wall 5.111 has a concave hollow-cylindrical geometry whoseaxis of symmetry is axis A. Housing body 5 has a substantiallyhollow-cylindrical shape axially on both sides of bottom 5.1. Housingbody 5 further has a machined stop surface 5.4 at an annular end facethereof.

In the exemplary embodiment presented here, to allow for axialdeformation of housing body 5, a plurality of slots 5.21, 5.22, 5.23,5.24 are machined into the housing body 5, each over a respectiveportion of its circumference. These extend radially completely throughthe wall of housing body 5, as can be seen, for example, in FIGS. 3 and4 in the regions between the hatched cross-sectional areas. Axiallyextending lands 5.31, 5.32, 5.33, 5.34 are located between these slots5.21, 5.22, 5.23, 5.24 in the circumferential direction. Slots 5.21,5.22, 5.23, 5.24 may be created, in particular, by a sawing process,leaving the axially extending lands 5.31, 5.32, 5.33, 5.34. Housing body5 is then configured such that the non-removed regions have a meanderingshape. Accordingly, lands 5.31, 5.32, 5.33, 5.34 are those regions ofthe remaining material which extend in a direction having an axialcomponent.

Slots 5.21, 5.22, 5.23, 5.24 can be grouped into pairs. In the figures,slots whose reference numerals have the same last digit are part of apair (thus, there are always two slots with the same reference numeral).In the exemplary embodiment presented here, housing body 5 has fourpairs of slots 5.21, 5.22, 5.23 and 5.34, respectively.

For example, a first pair of slots has the slots 5.21, which arearranged symmetrically about a point on axis A. The same holds for slots5.22, which can be considered as being part of a second pair of slots,and for the third and fourth pairs.

As can be seen from FIG. 5, the slots 5.21 of the first pair of slotsare here axially offset from the slots 5.22 of the second pair of slotsand circumferentially offset therefrom by about 90°.

Slots 5.21, 5.22, 5.23, 5.24 extend over a circumferential angle β ofabout 170°.

The slots 5.21 of the first pair of slots are located in a firstgeometric plane and the slots 5.22 of the second pair of slots arelocated in a second geometric plane that is axially offset from thefirst geometric plane. Both the first geometric plane and the secondgeometric plane are arranged such that the respective normal vector ofthe respective plane is oriented parallel to axis A. In the exemplaryembodiment presented here, the same considerations apply also to thethird and fourth pairs of slots 5.23; 5.24.

Similarly, lands 5.31, 5.32, 5.33, 5.34 can be grouped into four pairs.Here, housing body 5 has a total of eight lands 5.31, 5.32, 5.33, 5.34,of which six are visible in FIG. 5. A first pair of lands includes thelands 5.31, which are arranged symmetrically about a point on axis A.The lands 5.31 of the first pair are offset from one another by an angleα=180° in the circumferential direction. The same holds for lands 5.32,which can be considered as being part of a second pair of lands, and forthe lands 5.33, 5.34 of the third and fourth pairs. The lands 5.31 ofthe first pair of lands are axially offset from the lands 5.32 of thesecond pair of lands and circumferentially offset therefrom by acircumferential angle γ, here 90°. In the exemplary embodiment presentedhere, four pairs of lands 5.31, 5.32, 5.33, 5.34 are axially offset fromone another. Here, the lands 5.31, 5.33 of the first and third pairs areoffset from the lands 5.32, 5.34 of the second and fourth pairs by thesame circumferential angle γ.

Furthermore, housing body 5 is configured to have a first pair of lands,whose lands 5.31 are disposed in an imaginary plane whose normal vectoris oriented parallel to axis A. In other words, axis A orthogonallyintersects the aforesaid plane. The same considerations apply also tothe lands 5.32 of the second pair of lands, the plane in which theselands 5.32 are located being axially offset from the respective plane ofthe first pair of lands.

The scanning unit has lands 5.31, 5.32, 5.33, 5.34 with a slot 5.21,5.22, 5.23, 5.24 disposed axially therebetween, so that these lands5.31, 5.32, 5.33, 5.34 are axially offset from one another. Inparticular, slot 5.22 is disposed between the aligned and axially offsetlands 5.31, 5.33. Similarly, slot 5.23 is disposed between the alignedand axially offset lands 5.32, 5.34.

In the exemplary embodiment presented here, housing body 5 is formed asa single piece or component, except for sleeve 5.11. In particular,housing body 5 is made from an aluminum material.

During assembly of the scanning unit, circuit board 1, together withcontact carrier 4 and first elastic element 6, is assembled with housingbody 5, forming an assembly such as is shown, for example, in FIG. 4.Accordingly, contact carrier 4 extends into opening H. Elastic element 6is disposed between inner wall 5.111 of opening H and outer wall 4.2 ofcontact carrier 4 under radial preload; i.e., such that it is radiallycompressed. This preload causes contact carrier 4 to be centered withrespect to inner wall 5.111 of opening H without further action. Due tothe design of housing body 5 and the dimensioning of circuit board 1,circuit board 1 is radially spaced from housing body 5 by a first gap Gr(FIG. 4).

To ensure accurate operation of the entire angle-measuring device, it isnot only important that the circuit board 1 with detector assembly 2 becentered with respect to axis A, but it is also important in thisconnection to establish a defined axial position of circuit board 1. Inthe exemplary embodiment presented here, first surface 1.1 of circuitboard 1 is mounted flush with stop surface 5.4 of housing body 5.

To this end, initially, circuit board 1 is pushed into housing body 5 asfar as possible; i.e., as far as it will go. Then, an adhesive 8 isintroduced into circumferential gap Gr. Subsequently, stop surface 5.4is pressed onto a plane surface. Then, contact carrier 4 is movedrelative to opening H until circuit board 1 contacts the plane surfaceand the above-mentioned flush arrangement is obtained. In thisconnection, it may be advantageous to press contact carrier 4 towardcircuit board 1 using an auxiliary mounting tool. In this position,second surface 1.2 of circuit board 1 does not contact housing body 5,but rather an axial second gap Ga is present, as a result of which thenot yet cured adhesive 8 creeps into this second gap Ga due to capillaryeffects. Due to the axial preloading of housing body 5 and the axialcompressive force on contact carrier 4, it is ensured that circuit board1 and stop surface 5.4 remain in an exactly flush position. Thus, inthis phase, first gap Gr and second gap Ga are filled with an adhesive 8(FIG. 6), the adhesive 8 subsequently being cured, for example, in aheating furnace. After curing of adhesive 8, circuit board 1 is rigidlyand, in particular, torsionally rigidly attached to housing body 5, sothat the axial preloading of housing body 5 now can be removed. Thus,electronic components 3.1 are effectively shielded from externalinfluences, such as from ingress of lubricants or moisture, as well asfrom mechanical influences.

The scanning unit of FIGS. 3 through 5 and an angular scale 9 togetherform an angle-measuring device as shown in FIG. 6, which is hereembodied as an inductive angle-measuring device, and thus is based on aninductive measurement principle. In the exemplary embodiment presentedhere, angular scale 9 is configured as an annular circuit board on whichconductive and non-conductive regions; i.e., regions of differentelectrical conductivity, are provided in a periodic sequence and atidentical graduation steps. Angular scale 9 is non-rotatably connectedto a hub 15.

FIG. 6 shows an angle-measuring device which is equipped with theinductive scanning unit and mounted to a motor. The motor is provided inits stator portion with a brake including an armature plate 12. Themotor further has a shaft 13 which is rotatable relative to a housing ofthe motor and relative to armature plate 12. Hub 15 is non-rotatablyconnected to shaft 13 in such a way that a precisely adjusted air gaphaving a gap width D is provided between circuit board 1 and angularscale 9. To this end, shaft 13 has a first internal thread 13.1 that canmesh with an external thread of hub 15. This allows hub 15 to be axiallydisplaced relative to shaft 13 through suitable relative rotationbetween shaft 13 and hub 15. During mounting of hub 15 to shaft 13,initially, hub 15 is screwed into shaft 13, the spacing or gap width D(here, for example, 1.4 mm) between the top edge of housing 5 and thetop surface of angular scale 9 being precisely set using an auxiliarytool. Once this position is reached, a central bolt 16 is turned into asecond (smaller) internal thread 13.2 of shaft 13. As a result, thethreads of shaft 13 and hub 15 are clamped against one another,whereupon the angular scale 9 carrying the graduation structure isnon-rotatably fixed to shaft 13.

After that, the scanning unit, in particular housing body 5, is mountedto the armature plate 12 of the motor. To prevent relative rotation ofhousing body 5 with respect to armature plate 12, housing body 5 has akey 16 (FIG. 5), which is inserted into a groove of a so-called coilcarrier 14 provided on the stator. In addition, housing body 5 isaxially preloaded, so that housing body 5 is elastically deformed andthe axial gap widths of slots 5.21, 5.22, 5.23, 5.24 are reduced ascompared to the relaxed state. In accordance with FIG. 6, acircumferential retaining ring 11 (here a circlip) is installed in orderto maintain this axial preload. This ensures that the scanning unit willpermanently rest with the stop surface 5.4 of housing body 5 against thearmature plate 12 of the motor. Lifting of stop surface 5.4 off thearmature plate 12 is impossible, even in the presence of relativelystrong vibrations of the motor or upon the occurrence of shocks. Becausecircuit board 1 is disposed flush with stop surface 5.4, the distancebetween circuit board 1 and angular scale 9 is equal to the previouslyset gap width D.

Due to the above-described design, housing body 5 is axially flexiblebut torsionally and radially rigid.

During operation of the angle-measuring device, angular scale 9 rotatesabout axis A relative to the scanning unit. The angle-measuring deviceunder consideration has no integral bearing (i.e., no rolling-elementbearing or sliding bearing) to achieve relative rotatability, so that,in the exemplary embodiment presented here, it is a bearinglessangle-measuring device.

Thus, angular scale 9 and the scanning unit are rotatable relative toeach other, the angular scale 9 attached to shaft 13 rotating duringoperation of the angle-measuring device. Thus, the relative rotationalspeed between angular scale 9 and the scanning unit is also therotational speed between shaft 13 and stationary housing body 5. Duringoperation of the angle-measuring device, the non-rotating excitationcoils 10 of the stationary scanning unit generate a homogeneousalternating field which is modulated by angular scale 9 as a function ofthe angular position or angle of rotation of shaft 13. The modulatedelectromagnetic field generates angle-dependent signals in detectorassembly 2, which is also located on the scanning unit. The signalsgenerated by detector assembly 2; i.e., here the receiver windings, arefurther processed by evaluation electronics 3 so as to determine arelative angular position between the scanning unit and angular scale 9.The connector located in housing body 5; i.e., contacts 4.1 are broughtinto contact with a connecting cable, which is connected to subsequentelectronics.

It can generally be stated that the measurement system also responds tovariations in the actual scanning distance D. Scanning distance Dcontains information as to whether or not the brake disposed in thestator is engaged. This allows the scanning unit to determine thecurrent state of the brake (engaged or released) at any one time.

In the exemplary embodiment presented here, the angle-measuring deviceis designed according to what is known as “all-round scanning.” Thismeans, in particular, that the scanning unit is configured such thatangular scale 9 can be scanned by the scanning unit or by detectorassembly 2 over almost the entire circumference thereof, thus allowinggeneration of angle-dependent output signals. Accordingly, the scanningunit scans nearly the entire graduation structure of angular scale 9 toobtain a position signal.

FIG. 7 illustrates a second exemplary embodiment, which differs from thefirst by an alternative configuration of a housing body 5′. This variantallows the scanning unit to be mounted by clamping action. Housing body5′ has two axially extending slits 5.5 as well as wedge-shaped elements5.6, which can be displaced in the axial direction by clamping screws5.7. This allows the outer contour of housing body 5′ to be urgedradially outward in this area, which results in permanent clamping ofhousing body 5′, given suitable dimensioning of the motor housing.

While embodiments of the invention have been illustrated and describedin detail in the drawings and foregoing description, such illustrationand description are to be considered illustrative or exemplary and notrestrictive. It will be understood that changes and modifications may bemade by those of ordinary skill within the scope of the followingclaims. In particular, the present invention covers further embodimentswith any combination of features from different embodiments describedabove and below. Additionally, statements made herein characterizing theinvention refer to an embodiment of the invention and not necessarilyall embodiments.

The terms used in the claims should be construed to have the broadestreasonable interpretation consistent with the foregoing description. Forexample, the use of the article “a” or “the” in introducing an elementshould not be interpreted as being exclusive of a plurality of elements.Likewise, the recitation of “or” should be interpreted as beinginclusive, such that the recitation of “A or B” is not exclusive of “Aand B,” unless it is clear from the context or the foregoing descriptionthat only one of A and B is intended. Further, the recitation of “atleast one of A, B and C” should be interpreted as one or more of a groupof elements consisting of A, B and C, and should not be interpreted asrequiring at least one of each of the listed elements A, B and C,regardless of whether A, B and C are related as categories or otherwise.Moreover, the recitation of “A, B and/or C” or “at least one of A, B orC” should be interpreted as including any singular entity from thelisted elements, e.g., A, any subset from the listed elements, e.g., Aand B, or the entire list of elements A, B and C.

What is claimed is:
 1. A scanning unit for determining a relativeangular position of an angular scale that is rotatable about an axisrelative to the scanning unit, the scanning unit comprising: a circuitboard having a first surface and a second surface; a detector assemblywhich is disposed in a manner that enables scanning of the angular scalelocated opposite the first surface of the circuit board; evaluationelectronics; and a housing body comprising: slots extendingcircumferentially about the axis, lands in each case extending axiallybetween two of the slots such that the housing body is axially flexiblebut torsionally and radially rigid, wherein at least two of the landsare disposed axially offset to one another with one of the slotsdisposed axially therebetween, and a bottom disposed axially between theslots and the circuit board.
 2. The scanning unit as recited in claim 1,wherein the lands include a first pair of the lands, the lands of thefirst pair being disposed in a plane whose normal vector is orientedparallel to the axis.
 3. The scanning unit as recited in claim 2,wherein the lands include a second pair of the lands, the lands of thefirst pair being offset relative to the lands of the second pair by anangle in a circumferential direction.
 4. The scanning unit as recited inclaim 3, wherein the lands of the first pair are each offset by theangle of the same magnitude relative to the respective lands of thesecond pair in the circumferential direction.
 5. The scanning unit asrecited in claim 1, wherein the slots include a first pair of the slotsand has a second pair of the slots, the slots of the first pair beingaxially offset relative to the slots of the second pair.
 6. The scanningunit as recited in claim 5, wherein the slots of the first pair areoffset in the circumferential direction relative to the slots of thesecond pair.
 7. The scanning unit as recited in claim 1, wherein atleast one of the slots extends over a circumferential angle of at least70°.
 8. The scanning unit as recited in claim 7, wherein the at leastone of the slots extends over a circumferential angle of at least 100°.9. The scanning unit as recited in claim 1, wherein at least two of theslots extend over a circumferential angle of the same magnitude.
 10. Thescanning unit as recited in claim 1, wherein the housing body has a stopsurface having a normal which has a directional component parallel tothe axis.
 11. The scanning unit as recited in claim 1, wherein thehousing body is designed such that the bottom and the lands are a singlepiece.